2012
2012
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Record 97 of
Title:Fast algorithm for generating hologram of a 3D object by employing connection between layers
Author(s):Tang, Chuang(1); Yao, Bao-Li(1)Source: Guangdianzi Jiguang/Journal of Optoelectronics Laser Volume: 23 Issue: 11 DOI: Published: November 2012Abstract:An approximate method for generating computer-generated hologram (CGH) of a 3D object with speed 6 times faster than the conventional algorithm is presented. In the conventional coherent ray tracing (CRT) algorithm, a 3D object is sliced into many layers and treated as the collection of self-illuminated point light sources. The process of light ray propagating from every point of object to all the points on the hologram plane and interferred with the reference beam to form a CGH is simulated. In our proposed method, under the assumption that the depth of 3D object is much smaller than the recording distance, we just need to calculate the oblique distance between the first layer and the hologram plane, and then the oblique distances from the other layers to hologram plane can be obtained from their simple relation, thus the computational time is much reduced. The CGH is optically reconstructed and the quality of the reconstructed image is as good as that from the conventional algorithm.Accession Number: 20125015786949 -
Record 98 of
Title:Athermalization design of 8-12 μm infrared hybrid refractive/reflective/diffractive lenses for tank scan
Author(s):Liu, Feng(1); Sai, Jiangang(1); Zhao, Jianke(1); Xu, Liang(1); Hu, Dandan(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 41 Issue: 9 DOI: Published: September 2012Abstract:A range of 8-12 μm infrared hybrid refractive/reflective/diffractive athermalization lenses was designed for the needs of tank location system. The trouble of high machining accuracy with great difficulty in setting for bigbore primary mirror and secondary mirror was solved by employing a new- style Cassegrain system in which aspheric surfaces of primary mirror and secondary mirror were replaced by spheric surfaces. Athermalization design of infrared system was implemented by applying of diffractive elements with special temperature characteristics. This system has the feature of compact in frame, large caliber, long focus, high resolution and excellent image quality in range of -40-60°C, and meets the needs of general requirement and image quality demand for tank location.Accession Number: 20124915755280 -
Record 99 of
Title:Thermal management for CCD peformance of one space telescope
Author(s):Yang, Wengang(1); Wang, Yinghao(1); Feng, Liangjie(1); Wang, Chenjie(1); Ren, Guorui(1); Wang, Wei(1); Li, Chuang(1); Gao, Wei(1); Fan, Xuewu(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8420 Issue: DOI: 10.1117/12.971510 Published: 2012Abstract:A space telescope containing two CCD cameras is being built for scientific observation. The CCD detectors need to operate at a temperature below -65°C in order to avoid unacceptable dark current. This cooling is achieved through detailed thermal design which minimizes the parasitic load to 2K×4K array with 13.5 micron pixels and cools this detector with a combination of thermo electric cooler(TEC). This paper will describe detailed thermal design necessary to maintain the CCD at its cold operating temperature while providing the means to reject the heat generated by the TECs. It will focus on optimized techniques developed to manage parasitic loads including material selection, surface finishes and thermal insulation. The paper will also address analytical techniques developed to characterize TEC performance. Finally, analysis results have been shown the temperature of key parts. ? 2012 SPIE.Accession Number: 20131416168601 -
Record 100 of
Title:A joint method based on wavelet and curvelet transform for image denoising
Author(s):Wang, Hua(1); Cao, Jian-Zhong(1); Tang, Li-Nao(1); Zhou, Zuo-Feng(1)Source: Advanced Materials Research Volume: 532-533 Issue: DOI: 10.4028/www.scientific.net/AMR.532-533.758 Published: 2012Abstract:Wavelet transform is widely used and has good effect on image denoising. Wavelet transform has unique advantages in dealing with the smooth area of image but is not so perfect in high frequency areas such as the edges. However, curvelet transform can supply this gap when dealing with the high frequency areas because of the characteristic of anisotropy. In this paper, we proposed a new method which is based on the combination of wavelet transform and curvelet transform. Firstly, we detected the edges of the noisy-image using wavelet transform. Based on the edges we divided the image into two parts: the smoothness and the edges. Then, we used different transform methods to dispose different areas of the image, wavelet threshold denoising is used in smoothness while FDCT denoising is used in edges. Experimental results showed that we could get better visual effect and higher PSNR, which indicated that the proposed method is better than using wavelet transform or curvelet transform respectively. ? (2012) Trans Tech Publications, Switzerland.Accession Number: 20124615672146 -
Record 101 of
Title:Design of optical system for fusion reaction-rate measurement
Author(s):Yan, Ya-Dong(1); He, Jun-Hua(1)Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 20 Issue: 11 DOI: 10.3788/OPE.20122011.2389 Published: November 2012Abstract:Based on a plastic scintillator and an optic streak camera, a measuring system for fusion reaction-rate was designed, then the working princile and design method of the measuring system were addressed in detail. A piece of fused silica window was set just behind the plastic scintillator to protect optical elements from darkening after a long time exposure in scatted X rays and the ultraviolet crystals and other ultraviolet glass were selected to ensure the high system transmission. Furthermore, the image plane of the optical system was put onto a photocathode of the streak camera directly to remove the aperture non-matching of input optic system of the streak camera. Finally, a field mirror was put on the first image plane to reduce the max diameter of optical element from 160 mm to 120 mm. The designed optical system has a total length of 2 660 mm, magnification of 3:1 and its final lens is F/0.667 and transmission is 67%. Moreover, the time dispersion of the optical system is less than 7.3 ps. These results meet the experimental needs of different neutron yields and good experimental results have been obtained in a laser targeting experiment.Accession Number: 20125115818919 -
Record 102 of
Title:Research on reflective optical telescope system's wavefront aberration compensation method
Author(s):Duan, Xue Ting(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8415 Issue: DOI: 10.1117/12.978629 Published: 2012Abstract:Wavefront aberration measurement of the image quality of reflective telescope system which has a large aperture and long focal length is one of the frequently-used methods of high-precision test and alignment. It was widely used during the large aperture telescope manufacturing process. The influences of surface shape error of the reflective optical telescope system components were simulated and analyst by input the actual measuring data into the optical design software CODE V in this article. According to the test results compared to the alignment process, the accuracy of the simulation method was indicated. At the same time, the wavefront aberration optical compensation principle of the reflective optical telescope system was proved by the simulation of alignment. And in this article, the feasibility of the application of optical phase compensation alignment method was investigated. ? 2012 SPIE.Accession Number: 20131416168463 -
Record 103 of
Title:A robust image registration algorithm used for panoramic image mosaic
Author(s):Bo, Gao(1); Cao, Jianzhong(1); Zhou, Zuofeng(1); Qu, Enshi(1); Hua, Wang(1); Guo, Huinan(1)Source: Proceedings of 2012 International Conference on Image Analysis and Signal Processing, IASP 2012 Volume: Issue: DOI: 10.1109/IASP.2012.6425046 Published: 2012Abstract:The panoramic image has been widely used in social production, and has become an important topic in research on the field of image processing. For complex images with multiple scenes and other elements, the algorithm that is based on Harris cannot make image registration effectively. This paper proposes a method that combines Harris with SIFT, using the Harris algorithm with adaptive threshold to extract the corners and the SIFT descriptor to make the registration. It improved registration efficiency sub-effectively for the image in complex scenes, and generated a 360-degree panoramic image quickly. The experiments showed that the algorithm is adaptable and robust. ? 2012 IEEE.Accession Number: 20131016092694 -
Record 104 of
Title:A low loss ultra-narrowband negative-dispersion and large mode field area photonic crystal fiber for dispersion compensation
Author(s):Zhang, Yani(1,2,3); Huang, Jungang(2); Li, Kang(2); Gong, Yongkang(2,3); Copner, N.J.(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8426 Issue: DOI: 10.1117/12.921795 Published: 2012Abstract:A hexangular lattice dual-concentric-core photonic crystal fiber is proposed, which is composed of an inner core to be formed by missing a central air-hole, an outer ring core to be produced by reducing the size of the air-holes of the third ring and the double cladding circle air-holes along the direction of fiber length. Based on the full vector finite element method with anisotropic perfectly matched layers, its dispersion, leakage loss and mode field area are numerically investigated. Numerical results indicate that the proposed fiber shows large negative dispersion, strong confinement ability of guide mode, large effective mode area and low leakage loss and low sensitivity to the structure parameters. And the wavelength of high negative dispersion value can be adjusted by artificially choosing the parameters of the proposed PCF, such as Λ, d1 and f. The optimal design parameters with Λ=1.2μm, f=0.92, d1=0.52μm for proposed PCF are obtained to achieve ultra-narrowband negative dispersion value for dispersion compensation. For the optimal design, the dispersion value reaches as high as -3400 ps·km-1 nm-1 and the dispersion slope value is between -1000-6000 ps·km-1 nm-2 over C band (1.53-1.565μm). At wavelength of 1.55μm, the leakage loss is closed to 10-2 dB·m-1 and the corresponding area of effective mode is 36μm2. ? 2012 SPIE.Accession Number: 20122315100404 -
Record 105 of
Title:Design of precision strut assembly made from carbon fiber composite
Author(s):Li, Chuang(1); Ren, Guo-Rui(1); Wang, Wei(1); Fan, Xue-Wu(1)Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 20 Issue: SUPPL. DOI: 10.3788/OPE.20122013.0328 Published: December 2012Abstract:To satisfy the requirements of the installation truss of a space optical telescope for the weight, strength, stiffness and the thermal stability, a hexapod mainly composed of 6 Carbon Fiber Reinforced Plastic (CFRP) struts and 6 titanium alloy interface brackets was designed to mount the optical telescope onto a satellite payload module. Each interface bracket of the hexapod with a weight of 6.3 kg has a pair of heads and each head has two orthogonal flexures as virtual pivots without clearance to provide the flexure mount. By using finite element method, the modal frequency and the buckling factors of the assembly for the telescope and the hexapod were analyzed, and the stresses and strains of the hexapod under 1 g gravity load were studied. The low-stress assembly of hexapod components was performed with the aid of a strain measuring system. The results of vibration tests show that the first resonance frequency of the optical telescope with the hexapod is about 70 Hz, the maximum stress of the bottom flexure of the upper bracket is 160.6 MPa during the qualified level vibration test under a acceleration input of 7g, and vibration response in high frequency decays significantly. These results prove that the carbon fiber hexapod has good accuracy and can meet the requirements.Accession Number: 20132216372323 -
Record 106 of
Title:Surface simulation of tilt mirror based on contact and integrated simulation method
Author(s):Xu, Guangzhou(1); Ruan, Ping(1); Li, Ting(1); Li, Fu(1); Lu, Di(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 41 Issue: 5 DOI: Published: May 2012Abstract:To check whether the designed tilt mirror's surface satisfies the design requirement under the exterior loads, and to research the surface change rule of tilt mirror under the bolt pretightening force and gravity in different direction, the tilt mirror was analyzed using contact nonlinear finite element method. The surface displacement of tilt mirror was processed using data processing algorithm based on Zernike polynomials in order to eliminate the rigid displacement. The surface parameter after eliminating the rigid displacement and distributed curve of the rigid displacement factor were gained. The result demonstrates that the rigid displacement appeared is obvious under the exterior loads and the piston term occupies the chief aspect of the whole rigid displacement compared to the tilt term. The rigid displacement can be eliminated effectively using the surface processing algorithm based on integrated simulation method. The surface has the slight difference under the gravity in different direction. Compared to the bolt pretigtening force, the gravity has a small influence on the tilt mirror surface. The tilt mirror surface simulation under the bolt pretightening force makes sense for designing and assembling the tilt mirror and also shows engineering applicability of the surface simulation based on contact method.Accession Number: 20122915259966 -
Record 107 of
Title:Interactions of two humps of dipoles in anisotropic nonlinear media
Author(s):Zhang, Yiqi(1,2); Zhang, Yanpeng(1); Zhang, Meizhi(3); Lu, Keqing(2,4)Source: Optics and Laser Technology Volume: 44 Issue: 6 DOI: 10.1016/j.optlastec.2012.01.028 Published: September 2012Abstract:Propagation of dipoles and superposed dipoles in anisotropic nonlinear medium is investigated. The two humps of the dipoles will repel each other if attraction between them is smaller than repulsion, while if the former is larger than the latter, they attract. If there is phase gradient on the input dipoles or the energy distribution of the dipoles does not along the boundary directions of the medium, the dipoles will exhibit incomplete rotation during propagation. ? 2012 Elsevier Ltd. All rights reserved.Accession Number: 20121414920126 -
Record 108 of
Title:An improved Nyquist-Shannon irregular sampling theorem from local averages
Author(s):Song, Zhanjie(1); Liu, Bei(2); Pang, Yanwei(3); Hou, Chunping(3); Li, Xuelong(4)Source: IEEE Transactions on Information Theory Volume: 58 Issue: 9 DOI: 10.1109/TIT.2012.2199959 Published: 2012Abstract:The Nyquist-Shannon sampling theorem is on the reconstruction of a band-limited signal from its uniformly sampled samples. The higher the signal bandwidth gets, the more challenging the uniform sampling may become. To deal with this problem, signal reconstruction from local averages has been studied in the literature. In this paper, we obtain an improved Nyquist-Shannon sampling theorem from general local averages. In practice, the measurement apparatus gives a weighted average over an asymmetrical interval. As a special case, for local averages from symmetrical interval, we show that the sampling rate is much lower than that of a result by Grchenig. Moreover, we obtain two exact dual frames from local averages, one of which improves a result by Sun and Zhou. At the end of this paper, as an example application of local average sampling, we consider a reconstruction algorithm: the piecewise linear approximations. ? 1963-2012 IEEE.Accession Number: 20123515380383